(1) Field of the Invention
The present invention relates to an applicator of a liquid, and particularly relates to an applicator which stores an applying liquid such as a correcting liquid, water-color or oil-based ink, a cosmetic etc., and which applies the liquid onto a surface such as a sheet of paper.
(2) Description of the Prior Art
Japanese Utility Model Application Laid-Open Hei 5 No. 51,480 discloses an applicator which includes: a barrel member (applying liquid container) storing a liquid such as a correcting liquid as an applying liquid; a holder (tip) having a ball house with an ejecting opening at the front end thereof through which the liquid is ejected; and a ball (spherical applying member) which is held in the ball house and urged forward so that part of the ball projects outside from the ejecting opening.
The ball is held in the ball house in such a manner that it abuts an inward edge at the front part of the ball house while being movable in a separating direction from the edge. As the ball abuts against or separates from the edge, the ejecting opening is closed or opened.
Formed at the rear part of the ball house is a ball seat which supports the rear side of the ball when the ball is pressed against an applied surface and moved rearward. A liquid conduit for conducting the liquid from the barrel body to the ball house is formed substantially in a center of the cross-section of the ball seat. A moving piece (pressing means) urged by a spring is disposed through the liquid conduit, and its front end abuts the rear side of the ball to elastically press the ball forward.
When a user uses a conventional applicator thus configured and causes the ball to press an applied surface, the ejecting opening is released while the rear side of the ball is brought into contact with the ball seat. In this condition, as the ball is made to roll, it is possible to apply the liquid in desired places on a surface, referred to herein as the applied surface.
Meanwhile, in the aforementioned conventional applicator, when the ball is pressed against the applied surface and forced to move backward, the rear side of the ball blocks the liquid conduit, therefore it cannot be expected that the liquid is well supplied through the liquid conduit. Accordingly, some or several longitudinal grooves are formed on the inner wall of the liquid conduit, along the conducting direction, so that small clearances formed between the longitudinal grooves and the ball may allow the liquid to enter the ball house.
However, when the user performs application with the device by rolling the ball over the applied surface, the ball will rotate with the rear side thereof pressed against the ball seat. Therefore, as the applicator is repeatedly used, the ball seat wears out and consequently the longitudinal grooves, which are the only supplying channel of the liquid, could be blocked, preventing supply of the liquid into the ball house.
The above problems stand out especially when the viscosity of the liquid used is low or when the liquid contains pigments.
That is, when the liquid has high viscosity, the liquid itself effectively functions as a lubricant for alleviating the abrasion of the ball seat. On the other hand, if the viscosity of a liquid used is low, the lubricating power is ineffective. Therefore, the ball seat is highly susceptible to wear. Specifically, if the viscosity of a liquid is less than 30 cps, the abrasion of the ball seat becomes a major factor in causing liquid delivery deficiencies.
When the applying liquid is a correcting liquid containing organic and/or inorganic pigments or an ink containing pigments etc., presenting opacity, the liquid must contain titanium oxide and the like, which behave as polishing agents in the aforementioned wearing process, thus further promoting the ball seat to be worn out.
Since some liquids used for devices of this kind contain pigments which are susceptible to sedimentation, an agitating member or members, such as balls, rods etc., are provided for agitating the liquid inside the barrel body. If such an applicator is stored for a prolonged period of time, the sediment adheres to the ball seat and thereabout to thereby block the channels formed by the aforementioned grooves. When the applicator is repeatedly used in this manner, reduction of the ejecting amount of the liquid will be accelerated by the combination of the wearing process and the blockage by the sediment.
To solve these problems, the inner diameter of the ball house may be enlarged in order to increase the clearance between the ball and the inner wall of the ball house. This configuration assures large opening sections of the longitudinal grooves, making it possible to prevent the passage of the liquid from being clogged even if the ball seat has been worn out. In this case, however, the outside dimension of the holder must become large as the inner diameter of the ball house is made large. Therefore, the size of the holder becomes large relative to the ball size, and consequently the device becomes difficult to handle when characters etc., are to be written or small parts are to be applied.
Further, there is a concern that the clearance between the ball and the ball house will become larger than needed. In such a case, the liquid would flow out excessively, so that it would be impossible to eject the liquid in a proper amount.
The above problems occur in the same way in the applicator disclosed in Japanese Utility Model Application Laid-Open Sho 57 No. 193,578. A ball-point pen disclosed in Japanese Utility Model Application Laid-Open Sho 52 No. 39,228 has a pair of balls arranged in the length-wise direction inside a ball holding portion (corresponding to the aforementioned ball house) in order to reduce the abrasion of a ball receiving portion (corresponding to the aforementioned ball seat). In this configuration, however, the balls are held in close contact with projections formed on the inner wall of the ball holding portion, so that when the two balls are pressed backward at writing, the inner ball completely blocks the liquid conduit formed in the center of the ball receiving portion. As a result, the only passage of supplying ink (corresponding to the aforementioned liquid) assured is ink conducting grooves (corresponding to the aforementioned longitudinal grooves), which cannot allow sufficient supplying of ink. Further, in the configuration disclosed in Japanese Utility Model Application Laid-Open Sho 52 No. 39,228, the sealing performance at the tip opening portion (corresponding to the ejecting opening) is dependent upon the clearance between the ball and the opening portion. That is, for some types of liquids, closing and opening of the opening portion cannot be effected well enough, possibly causing deficiencies such as liquid leaking.